An exhaust manifold of a turbocharged engine is exposed to thermal loads not present in a typical cast iron or stainless steel exhaust manifold of a naturally aspirated engine. One approach to compensate for increased temperature loads and reduce manifold degradation includes a ferritic or austenitic stainless steel cast exhaust manifold. Such steel materials may reduce the thermal expansion of the manifold, increase the thermal insulation of the manifold and protect the manifold from creep degradation, for example. A further approach involves cooling via a coolant jacket encompassing a major portion of the exhaust manifold.
The inventors herein have recognized issues with the above described approaches. The inclusion of ferritic or austenitic stainless steel materials in an exhaust manifold may significantly increase manifold cost in comparison to manifolds without such materials. Further, cooling the exhaust manifold via encompassing a majority or more of an exhaust manifold removes thermal energy that would otherwise improve both turbocharger and catalyst function and performance.
Accordingly, as a brief summary, devices, systems and methods are disclosed for a coolant jacket included in an exhaust manifold. In one example an exhaust manifold system includes a plurality of inlets to runners extending perpendicular a longitudinal manifold axis, an outlet passage distal from the runners, the outlet passage terminating with a manifold flange, and a coolant jacket including a coolant inlet and outlet both for coupling to a coolant system, and a collar fluidically coupling the coolant inlet and outlet, the collar adjacent the outlet passage and the manifold flange and decoupled from the runners.
In a further example a method of heating engine systems, the method includes combusting fuel in a cylinder of an engine, adsorbing heat from combusted fuel exhaust into a coolant via a coolant jacket, the coolant jacket including a collar, the collar only surrounding the circumference of an exhaust passage outlet adjacent an exhaust manifold flange, the outlet asymmetrically positioned at a first manifold end, distal from a plurality of exhaust runners, the outlet passage extending out away from a plane including the totality of runners and the outlet passage extending parallel from the runners away from inlets included in the runners, and the outlet passage terminating with a manifold flange, flowing heated coolant from an outlet of the coolant jacket to a heating circuit, the heating circuit including a heating element for at least one of a cabin heater, a catalyst, an injector, an intake air heater, and a positive crankcase ventilation system, and flowing combusted fuel exhaust to a turbine of a turbocharger, an amount of retained heat of combusted fuel exhaust greater than an amount of coolant adsorbed heat.
By including the collar water jacket surrounding the outlet passage, the exhaust manifold system may include lower-cost materials (e.g., a silicon molybdenum) while removing less thermal energy—thermal energy that can be used to increase turbocharger and catalyst performance. Another advantage is that the collar coolant jacket is a heat source (for example during engine warm up) for a heating element, such as in a cabin heater, a catalyst, an injector, an intake air heater, and/or a positive crankcase ventilation system.
It will be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description, which follows. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined by the claims that follow the detailed description. Further, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.